Collapsible tap



No. 624457. Patented may 2, |899.

W. D. BALCONI.

CULLAPSIBLE TAP.

pphcation led Jan. 23, 1899 '(No Model.)

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'NTTED STATES PATENT Finca.

WILLIAM D. BALCOM, OF NORWIOH, CNNECTICUT.

SPECIFICATION forming part of Letters Patent No. 624,157, dated May 2, 1899.

Application filed January Z3, 1899. Serial No. 7031113. (No model.)

To all whom t may] concern: Y

Be it known that I, WILLIAM D. BALcoM, a citizen of the United States, residing at Norwich, in the county of New London, State of Connecticut, have invented certain new and useful Improvements in Collapsible Taps, of which the following is afull, clear, and exact description.

This invention is in taps for machinists use; and my immediate object is to provide a novel form of tap in which the threadingdies may be collapsed so soon as the threading operation is completed in order that said tap may be quickly withdrawn Without having to unscrew it.

My said invention is fully illustrated in the accompanying drawings.

Figure 1 is a view of the same complete. Fig. 2 is a central longitudinal sectional view of said tap, showing the threading-dies in their operative or cutting positions. Fig. 3 is a view similar to Fig. 2, showing the said dies collapsed. Fig. 4 is a cross-sectional view taken on the line 2 2. Fig. 5 is a detached view of a plunger or spindle of peculiar form, by means of which the cutting-dies are expandedand collapsed.

Referring to the drawings, the letter a indicates the shank of my newly-invented tap, said shank being bored out at one end to form a central chamber a', Whose circumferential Wall is slotted radially, as at d2, to receive the threading-dies l). As here shown, four of the said threading-dies are provided,but the number is not material. formed upon its inner edge one or more lips b', that hook under the shell of shank ct, as seen in Fig. 4, and serve to prevent the dies from leaving the slots a2.

"Within the chamber ce" is a plunger having a shank portion c, that extends Well into said chamber. Said plunger is adapted to move endwisein the chamber a', and to attain such endwise movement a pin d is passed through the head thereof, whose opposite ends extend outward through slots CL3 in the shank a. The said opposite ends of the pin d enter an internally-cut double thread e, cut ina collar e, vwhich latter is mounted upon the shank a and is adapted torevolve thereon Vbetween an annular flange CL4 formed on said shank and a collar e2 properly located thereon. The

Each of said dies has collar e2 is provided with oppositelyextending handles e3, by means of which the same is rotated, such rotation causing the opposite ends of pin d to travel on the thread e and causing the said pin to travel in the slots a3 and correspondingly moving the plunger c Within the chamber d', the direction of such movement being dependent of course upon the direction of rotation of the collare. The outer or free end 0f the plunger is turned down, as at c', to enter a cap or plate g, that is fastened to the otherwise open end of the chamber a. Plate g thus serves to support the end of the plunger centrally in chamber a', but does not prevent the free endwisc movement of said plunger.

That portion of the plunger that is adjacent to the inner edges of the threading-dies is peculiarly formed and serves to force the dies outward and hold them there during the threading operation When the plunger is slid in one direction, and also serves to draw inward or collapse the said dies when slid. in the opposite direction, as l shall explain.

Near the front and rear ends of the inner edges of the dies b the plunger is provided with shoulders or enlargements Vc2 c3, that nearly iill the chamber d and which lie immediately under the ends of the dies when the plunger is moved outward-that is to say, toward the plate g-as illustratedin Fig. 2 of the drawings. These shoulders c2 c3 form a Jsubstantial backing to support the dies during the threading operation.

The dies are recessed in their inner edges, as at b2, to provide wedge-shaped portions b3, that point toward the plate g, and the plunger c is formed with an enlargement c4, whose inner end portion is cupped to provide a sharp annulus c5, that is of such diameter that it extends into the recesses b2 of the dies, as seen in Figs. 2 and 3 of the drawings.

lVhen the plunger is slid inward, the sharp edge cof the annulus engages the sharp edges b3 of the threading-dies and draws the said dies inward, (toward the plunger,) as seen in Fig. 3.

It Will thus be understood that the simple act of sliding the plunger outward results in forcing the dies into their operative or cutting posit-ions and that the act of sliding said IOO dies and allowing the complete tool to be lwithdrawn out of the tapped hole Without having to unscrew said tap.

Having thus described my invention, I claim-v A hollow shaft having its ends slotted to receive the dies, a series of dies placed in the slots and provided upon their inner sides With recesses, the Wedge-shaped portions b3, and the plate g, applied to the end of the shank to keep the dies in position, combined with an endWise-moving plunger, provided With the enlargements c3 c4, and an extension c which passes through the plate g, the inner end of the enlargement 'c4 being recessed so as to receive the wedge-shaped portions and the enlargement c3 fitting between the outer ends of the dies so as to support them while in operation, substantially as described.

Signed at Norwich, Connecticut, this 7th day of January, 1899.

WILLIAM D. BALCOM.

NVitnesses:

ALoNzo M. LUTHER, FRANK I-I. ALLEN. 

